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Fish Welfare for Disease Prevention

14 June 2013

ANALYSIS - The key to disease prevention is the maintenance of good fish welfare among the stock according to Dr Sunil Kadri the managing director of Europharma Scotland and Aquaculture Innovation.

Dr Kadri, speaking at a recent Federation of Veterinarians of Europe conference in Brussels said that fish welfare is a very wide term that has implications in other areas of aquaculture management.

And he warned that all too often disease management is seen as the means of managing fish health and is viewed separately from fish welfare. The whole picture of production measures together with disease treatment has to be taken into consideration to ensure full health and welfare.

Dr Kadri said that fish health management has come a long way over the decades and has been greatly improved by preventative measures, which are often used as a standard approach – such as the use of probiotics and vaccines.

However, he added that these measures are not without their problems and should not be used for an excuse for complacency among fish health managers.

He said that preventative measures such as vaccination can have problems with side effects and other issues come into play for maintaining health other than curing and preventing disease.

Many of the measures being used by fish health professionals are just fire fighting and the losses through disease can be severe and have not changed much over 20 years

“Vets react well with diagnostic tools, but it is fire fighting. We need a new paradigm,” he said.

He said that the veterinary community in general needs to become more aware of what actually takes place in the aquaculture environment to ensure the total health and welfare of the fish.

The veterinarians need to work with the people on the farms so that they can learn and the farmers can learn, he said.

“Health is a state of complete physical well-being and not merely the absence of disease – it is not about fish coping but performing too,” he said.

Dr Kadri said the most important aspect of fish health and welfare is water quality, including monitoring the quantities of carbon dioxide and heavy metals as well as the supply of water and the renewal rates.

Welfare considerations also have to take into account the water support systems such as the oxygen supply, boreholes and reservoirs.

Further welfare issues that impact on fish health are the stresses that the fish are placed under in loading on and off the farm and the stresses in transport and the need to mitigate potential mortality rates, which have an economic effect on the business.

“Effects of stress upon fish health are real and demonstrable,” he said.

Other issues of husbandry such as nutritional requirements, the type of feed, nutritional profile, pellet size and feed management also have to be taken into consideration.

He said that common pathogens often have subclinical effects and these need to be managed not only through veterinary intervention but also through husbandry practices.

“Veterinary diagnostic approach often involves ‘experts’, who have little or no connection with production,” he said.

Dr Kadri added that the industry needs to reduce losses to grow sustainably and this requires a paradigm shift in veterinary/health care.

He said there needs to be a move towards greater involvement with production and allowing preventative health/welfare management.


Chris Harris

Chris Harris

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